The present invention relates to pressure regulators for controlling the flow of gas, and more particularly relates to pressure regulators used for high pressure gaseous fuels such as compressed or liquified natural gas or hydrogen.
It is becoming increasingly common to use so-called alternative fuels, such as propane or natural gas, in internal combustion engines or hydrogen in fuel cells. Often such engines are converted to use one or two or more sources of fuel, such as gasoline and natural gas; the operator has the ability to switch between sources depending on the availability and price of these fuels.
Many vehicles are manufactured to operate on gasoline only and are converted to run on two or more fuels. The vehicles are manufactured with storage tanks for gasoline, pumps for moving the gasoline from the tank to the engine, and carburetors or fuel injectors for introducing the fuel and the required amount of air for combustion into the engine.
Gaseous fuels such as propane, natural gas, and hydrogen must be stored in pressurized cylinders to compress the gas into a manageable volume. Increasing the pressure to the highest level that can safely be handled by the pressurized storage cylinder increases the amount of fuel that can be stored in that cylinder and extends the distance that the vehicle can be driven to its maximum. Typical storage cylinder pressures range from 2000 to 5000 psig.
Internal combustion engines cannot operate at such a high pressure, and the pressure of the gas must be reduced to a level at which the engine can be operated safely.
The pressure must also be regulated as it is reduced to ensure that the pressure of the fuel entering the engine is nearly constant even as the pressure in the storage cylinder is reduced. At the same time, the pressure regulation must permit as much gas as possible to be removed from the storage cylinder, and thus permit the pressure in the storage cylinder to fall to as close to the operating pressure as possible. A high pressure difference across the pressure regulator means that unused fuel remains in the storage cylinder and is unavailable to the engine.
Conventional pressure regulators having one or more stages over which the pressure is reduced are well-known and have long been used to reduce the pressure and regulate the flow of compressed gases. Some of these are known as pressurebalanced regulators and use various arrangements of springs, diaphragms and machined parts to balance pressures and fluid flow over the various stages of the regulator. In this respect, a valve is typically mounted to a diaphragm opening and closing gas supply, thereby regulating gas flow.
The diaphragms in such pressure-balanced regulators are subjected to pressure fluctuations, causing stressing of the diaphragm. The diaphragm, being made of resilient material, is susceptible to mechanical fatigue and failure caused by the above-described stresses. Failure or rupture of the diaphragm is of particular concern where sealing provided by the associated valve is compromised, thereby exposing the diaphragm to the high gas pressures within the storage cylinder.
Similarly, overpressure conditions resulting from leakage through the valve seal can overstress the valve, also leading to premature failure of this component.
In one broad aspect, the present invention provides a pressure regulator comprising a housing including a high pressure chamber and a low pressure chamber, a moveable pressure boundary member configured to isolate the high pressure chamber from the low pressure chamber, a pintle valve, including a pintle stem and a pintle retainer, the pintle stem extending through the moveable pressure boundary member and carrying the pintle retainer, the pintle retainer being disposed in the low pressure chamber, and a resilient member interposed between the pintle retainer and the moveable pressure boundary member.
In a further aspect, the present invention provides a pressure regulating valve comprising a body, a low pressure chamber, a fluid passage disposed within the body, a valve seat disposed within the fluid passage, an orifice disposed within the valve seat and communicating with the fluid passage, a valve pintle configured for sealing the orifice, including a pintle stem and a pintle retainer, the pintle stem extending through the moveable pressure boundary member and carrying the pintle retainer, the pintle retainer disposed in the low pressure chamber, a moveable pressure boundary member, coupled to the valve pintle, and configured to isolate the fluid passage from the low pressure chamber, and a resilient member interposed between the pintle retainer and the moveable pressure boundary member.
In yet another aspect, the present invention provides a pressure regulating valve comprising a body, a fluid passage disposed within the body, a valve seat disposed within the fluid passage, an orifice disposed in the valve seat and communicating with the fluid passage, a valve pintle configured for sealing the orifice, a moveable pressure boundary member, coupled to the valve pintle, comprising a diaphragm, and a detent configured to limit movement of the moveable pressure boundary member.
In yet a further aspect, the present invention provides a pressure regulating valve comprising a housing, including a low pressure chamber and a high pressure chamber, a moveable pressure boundary member, configured to isolate the high pressure chamber from the low pressure chamber and a detent, disposed in the low pressure chamber, and configured to limit movement of the moveable pressure boundary member.
By providing a resilient member between the pintle nut and the diaphragm plate, overstressing of the pintle valve during overpressure conditions is mitigated. Further, by providing an uninterrupted surface for contacting and supporting the diaphragm during overpressure conditions, failure of the diaphragm is also mitigated.